docs: add missing doc references from async client (#1665)

Author: pcriadoperez

binance/async_client.py

@@ -2054,6 +2054,8 @@ async def futures_symbol_ticker(self, **params):
 
     futures_symbol_ticker.__doc__ = Client.futures_symbol_ticker.__doc__
 
+    futures_symbol_ticker.__doc__ = Client.futures_symbol_ticker.__doc__
+
     async def futures_orderbook_ticker(self, **params):
         return await self._request_futures_api("get", "ticker/bookTicker", data=params)